Normally, cooler, nutrient-rich water flows up from the depths into the California Current. This supplies nutrients that fish, kelp forests and other marine life depend on. But the process can be reversed by El Niño, cutting off access to zooplankton, small fish and other prey.
"We're getting a completely different ocean," Chris Lowe, a professor of marine biology and director of the Shark Lab at Long Beach State University, told USA Today .
Must adapt
Shark Lab is now warning fishermen, surfers and others that they may have to share the ocean with animals they are not used to. And that they may have to adapt for their own safety.
Both tiger sharks and bull sharks have been caught off the coast of California during previous El Niño events. Hammerheads that follow mako may be more aggressive when hunting, Lowe says.
During the 2015–2016 El Niño, two hammerhead shark bites were reported at sea. This year, with the marine heatwave and the rapidly developing El Niño phenomenon, scientists expect to see more similar events.
One of the most dramatic changes off the coast of California concerns great white sharks, especially large numbers of juveniles, which follow the warmer waters. The phenomenon has been known for some time. In 2015, when El Niño was also strong, there was a buildup of warm water off the coast and the number of juveniles doubled.
Injuries from stingrays
But the increase in great white sharks is not necessarily a danger to swimmers. A bigger concern is stingrays - a favorite food for young sharks. Already today, lifeguards in California treat around 10,000 such injuries a year, and Chris Lowe fears that the number of injuries will skyrocket.
Another unwelcome guest is the extremely poisonous yellow-bellied sea snake, which only appears during unusually warm periods.
Now, scientists are growing concerned about the long-term effects of the warmed waters associated with the El Niño phenomenon. Douglas McCauley, director of the Benioff Ocean Initiative, talks about a double whammy as El Niño adds additional heat to the heat wave and climate change that already exists.
It's going to be a strange and interesting fall and winter. I can tell you it's not going to be normal. We're following all aspects of the ocean with great interest, including the sharks.
El Niño and La Niña are phases of the El Niño-Southern Oscillation (ENSO) weather cycle. El Niño warms the surface waters of the eastern Pacific Ocean, while La Niña cools them.
El Niño occurs on average every two to seven years and typically lasts nine to twelve months. It often peaks around Christmas, hence the name El Niño (the boy child).
El Niño effects such as increased rainfall typically affect parts of southern South America, the southern United States, the Horn of Africa, and Central Asia, while severe drought can occur over Australia, Indonesia, and parts of southern Asia.
The 2023–2024 El Niño is said to be one of the five strongest ever recorded.
Source: WMO, SMHI, NOAA
